Abstract: An electronic control system for controlling a sequence of operations on products moving on an indexing conveyor. The electronic control system is illustrated as controlling a sequence of operations, carried out at various work stations, on cartons in a packaging machine, such as filling operations, sealing operations, and clean-in-place operations on carton filler heads. A limit switch carton detector detects the presence or absence of cartons on the indexing conveyor of the packaging machine and feeds such carton information into a first shift register, which in turn feeds the carton position information into a first "and" gate. A limit switch machine timing indicator functions to feed a first machine timing signal into said first shift register, and into a machine cycle counter. An output signal from the machine cycle counter is fed into a sequence selector which products a sequence signal that is fed to said first "and" gate, which in turn produces a filler sequence signal.